The purpose of the proposed conference is to bring together a broad spectrum of investigators to focus on the pathogenesis of the spondyloarthropathies. Recent advances in molecular biology, basic immunology and microbiology have generated a great deal of new information concerning the structure and function of class I MHC molecules, the potential role of molecular mimicry in disease pathogenesis, as well as the possible role of heat shock proteins in generating inflammatory responses. In addition, recent observations on the epidemiology and clinical expression of the spondyloarthropathies as well as the development of related conditions in HIV infected individuals have generated new insights into the disease process. The goal of the meeting is to bring together basic scientists and clinical investigators in an attempt to integrate this new information and generate testable hypotheses concerning the immunopathogenesis of the spondyloarthropathies. The four day meeting will include workshops devoted to: 1) The structure of class I MHC molecules; 2) Functional properties of class I MHC molecules; 3) Tolerance and autoimmunity in transgenic animals; 4) Heat shock proteins and disease pathogenesis; 5) Bacterial pathogenesis and molecular mimicry; 6) Epidemiology of B27 associated conditions; and 7) Clinical aspects of ankylosing spondylitis and reactive arthritis. This will be the first international symposium devoted to the topic that will bring together investigators from every discipline germane to understanding the pathogenesis of the spondyloarthropathies.